1. Field of the Invention
The present invention refers to an automatic analyzer for the assay of liquid samples, said automatic analyzer comprising a mixing chamber which is followed by an analyzing block including an evaluating unit, said mixing chamber comprising at least one inlet opening for air and water respectively and being connected to an outlet opening for the analyzed liquid.
2. Description of the Prior Art
As an example of the prior art, FIG. 1 shows an automatic analyzer for the selective determination of ions, e.g. Li+, K+, C1xe2x88x92, in liquid samples of biological substances such as blood or urine. The samples are placed on a sample platform in separate containers. By means of an automatic pipette arm 12 small amounts of the samples are serially supplied to a mixing chamber. The chamber essentially consists of an upwardly open, cylindrical vessel having a continuously tapering bottom. Inlet openings for air and water, respectively, are laterally connected to the top of this vessel, and two outlet openings are connected to its bottom. The liquid samples delivered by the pipette needle are homogenized by means of an air vortex generated by an opening, and supplied by an outlet opening and a connecting duct to the measuring channel of an analyzing block, such as an electrode block. A second inlet opening mainly serves for the supply of rinsing water and an outlet opening for the extraction of the latter and of possible excess liquid (waste).
The measuring channel of the analyzing block is provided with several ion-selective electrodes and a reference electrode connected thereto which measure the ion concentration of the above-mentioned ions and output the measuring results by means of an electronic evaluating system. Finally, the sample liquid is discharged into a collector 25 for disposal.
The operation of automatic analyzers of the represented kind should be as free of disturbances as possible. However, since the analyzed liquids come from a large number of sources, this aim can only be attained within certain limits. In particular, frequent problems are caused by small particles such as coaguli which may choke the analyzer, thereby resulting in incorrect analyses or even rendering the measurements impossible. In such cases, the critical components must be disassembled and cleaned, thereby causing complications and time losses.
It is an object of the present invention to provide an improvement of known automatic analyzers by preventing the described obstructions as much as possible.
The present invention provides for an automatic analyzer wherein the mixing chamber is disposed in a dedicated, exchangeable unit, and the outlet opening for the analyzed liquid is associated with a particle collecting trap.
In particular, an advantage of the present invention is that the mixing chamber is easily exchangeable, so that impairments of the operation of the automatic analyzer by an obstruction of the mixing chamber by a particle, e.g. a coagulum, are easily and quickly eliminated. Furthermore, the mixing chamber design of the present invention allows quick and effective cleaning, so that possible particles in its outlet channel are easily removed.